RESUMO
BACKGROUND: Propofol effect-site time course models included in TCI systems have been under discussion. We hypothesized that the rate of administration is a major contributor affecting the construction of a useful effect-site model: yielding different plasmatic concentrations, loss of consciousness may occur by different mechanisms more complex than the pharmacological effect-site. METHODOLOGY: ASA III patients were randomized in two groups: rapid induction (RI) received TCI of propofol effect-site (CeCALC) 5.4 µg/mL (modified Marsh model), and slow induction (SI) propofol infusion of 10 mg/kg/hour. A neurologist, blinded to induction method, performed neurological assessments using the FOUR score until the loss of consciousness (LOC). At LOC, the presence of brain stem reflexes, EEG index (PSI) and infusion time/mass of drug were registered. Fisher's exact test was used to describe differences between brain stem reflexes and respiration components of the FOUR score and CeCALC for 4 propofo models at LOC time. RESULTS: 16 patients divided in two groups were included. All patient in SI had brainstem reflexes free at LOC. In the RI, all patients had brain stem reflexes abolished and 1 patient had B and R of 4 points in the FOUR score (brain stem reflexes unaffected; P < .001). CeCALC at LOC time were contradictory at LOC in both groups and using 4 different Pk/Pd models. CONCLUSIONS: Depending of the infusion rate, propofol CeCALC at LOC calculated by different Pk/Pd models could be the source of confuse data to be used to guide the state of general anesthesia.
Assuntos
Propofol , Anestesia Geral , Anestésicos Intravenosos , Humanos , Inconsciência/induzido quimicamenteRESUMO
Antecedentes: Se han debatido los modelos de curso temporal del sitio de efecto del propofol. Nosotros supusimos que la tasa de administración es un gran factor contributivo que afecta a la construcción de un modelo de sitio de efecto útil: elaborando distintas concentraciones plasmáticas, la pérdida de consciencia puede producirse debido a diferentes mecanismos más complejos que el sitio del efecto farmacológico. Metodología: Se aleatorizaron pacientes ASAI-II en dos grupos: el grupo de inducción rápida (IR) recibió TCI de sitio de efecto de propofol (CeCALC) 5,4μg/ml (modelo Marsh modificado) y el grupo de inducción lenta (IL) recibió una infusión de propofol de 10mg/kg/h. Un neurólogo, a quien se ocultó el método de inducción, realizó las evaluaciones neurológicas utilizando la escala FOUR hasta lograr la pérdida de consciencia (LOC). Una vez lograda, se registraron la presencia de reflejos troncoencefálicos, el índice EEG (PSI) y el tiempo de infusión/masa del fármaco. Se realizó la prueba exacta de Fisher para describir las diferencias entre los reflejos troncoencefálicos y los componentes respiratorios de la escala FOUR, así como CeCALC para los 4 modelos de propofol en el momento de la LOC. Resultados: Se incluyeron 16 pacientes, divididos en dos grupos. Todos los pacientes del grupo IL tuvieron reflejos troncoencefálicos libres en LOC. En el grupo IR, en todos los pacientes se suprimieron los reflejos troncoencefálicos, y un paciente obtuvo 4 puntos B y R en la escala FOUR (reflejos troncoencefálicos no afectados; p<0,001). CeCALC en el momento de LOC fue contradictorio en ambos grupos, utilizando 4 modelos Pk/Pd diferentes. Conclusiones: Dependiendo de la tasa de infusión, CeCALC de propofol en el momento de la LOC, calculado mediante modelos Pk/Pd diferentes, podría ser la fuente de datos de confusión a utilizar para guiar el estado de la anestesia general.(AU)
Background: Propofol effect-site time course models included in TCI systems have been under discussion.We hypothesized that the rate of administration is a major contributor affecting the construction of a useful effect-site model: yielding different plasmatic concentrations, loss of consciousness may occur by different mechanisms more complex than the pharmacological effect-site. Methodology: ASA I-II patients were randomized in two groups: rapid induction (RI) received TCI of propofol effect-site (CeCALC) 5.4μg/mL (modified Marsh model), and slow induction (SI) propofol infusion of 10mg/kg/hour. A neurologist, blinded to induction method, performed neurological assessments using the FOUR score until the loss of consciousness (LOC). At LOC, the presence of brain stem reflexes, EEG index (PSI) and infusion time/mass of drug were registered. Fisher's exact test was used to describe differences between brain stem reflexes and respiration components of the FOUR score and CeCALC for 4 propofol models at LOC time. Results: 16 patients divided in two groups were included. All patient in SI had brainstem reflexes free at LOC. In the RI, all patients had brain stem reflexes abolished and 1 patient had B and R of 4 points in the FOUR score (brain stem reflexes unaffected; P<.001). CeCALC at LOC time were contradictory at LOC in both groups and using 4 different Pk/Pd models. Conclusions: Depending of the infusion rate, propofol CeCALC at LOC calculated by different Pk/Pd models could be the source of confuse data to be used to guide the state of general anesthesia.(AU)
Assuntos
Humanos , Masculino , Feminino , Propofol/administração & dosagem , Propofol/efeitos adversos , Anestésicos Intravenosos , Inconsciência/induzido quimicamente , Anestesiologia , Anestesia GeralRESUMO
BACKGROUND: Propofol effect-site time course models included in TCI systems have been under discussion. We hypothesized that the rate of administration is a major contributor affecting the construction of a useful effect-site model: yielding different plasmatic concentrations, loss of consciousness may occur by different mechanisms more complex than the pharmacological effect-site. METHODOLOGY: ASA I-II patients were randomized in two groups: rapid induction (RI) received TCI of propofol effect-site (CeCALC) 5.4µg/mL (modified Marsh model), and slow induction (SI) propofol infusion of 10mg/kg/hour. A neurologist, blinded to induction method, performed neurological assessments using the FOUR score until the loss of consciousness (LOC). At LOC, the presence of brain stem reflexes, EEG index (PSI) and infusion time/mass of drug were registered. Fisher's exact test was used to describe differences between brain stem reflexes and respiration components of the FOUR score and CeCALC for 4 propofol models at LOC time. RESULTS: 16 patients divided in two groups were included. All patient in SI had brainstem reflexes free at LOC. In the RI, all patients had brain stem reflexes abolished and 1 patient had B and R of 4 points in the FOUR score (brain stem reflexes unaffected; P<.001). CeCALC at LOC time were contradictory at LOC in both groups and using 4 different Pk/Pd models. CONCLUSIONS: Depending of the infusion rate, propofol CeCALC at LOC calculated by different Pk/Pd models could be the source of confuse data to be used to guide the state of general anesthesia.
RESUMO
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